Innerspring assemblies, for mattresses, furniture, seating and other resilient structures, were first assembled by hand by arranging coils or springs in a matrix and interconnecting them with lacing or tying wires. The coils are connected at various points along the axial length, according to the innerspring design. Machines which auromatically form coils have been mated with various conveyances which deliver coils to an assembly point. For example, U.S. Pat. Nos. 3,386,561 and 4,413,659 describe apparatus which feeds springs from an automated spring former to a spring core assembly machine. The spring or coil former component is configured to produce a particular coil design. Most coil designs terminate at each end with one or more turns in a single plane. This simplifies automated handling of the coils, such as conveyance to an assembler and passage through the assembler. The coil forming machinery is not easily adapted to produce coils of alternate configurations, such as coils which do not terminate in a single plane.
The timed conveyance of coils from the former to the assembler is always problematic. Automated production is interrupted if even a single coil is misaligned in the conveyor. The conveyor drive mechanism must be perfectly timed with operation of the coil former and a transfer machine which picks up an entire row of coils from a conveyor and loads it into the innerspring assembler.
The spring core assembly component of the prior art machines is typically set up to accommodate one particular type of spring or coil. The coils are held within the machine with the base or top of the coil fit over dies or held by clamping jaws, and tied or laced together by a helical wire or fastening rings. This approach is limited to use with coils of particular configurations which fit over the dies and within the helical lacing and knuckling shoes. Such machines are not adaptable to use with different coil designs, particularly coils with a terminal convolution which extends beyond a base or end of the coil. Also, these types of machines are prone to malfunction due to the fact that two sets of clamping jaws, having multiple small parts and linkages moving at a rapid pace, are required for the top and bottom of each coil.